CN101092050A - Method for producing hardened film applied to in-mold decoration injection molding - Google Patents

Abstract

The invention relates to an injection molding process for in-mold decoration. The invention aims to provide a method for manufacturing a hardened film applied to in-mold decoration injection molding, which can avoid the cracking phenomenon of the hardened film when the hardened film is deeply molded in the in-mold decoration Injection Molding (IMD) process, promote the in-mold decoration Injection Molding (IMD) process to be largely used by the industry, and achieve the effects of improving the production yield, efficiency and colorization and reducing the environmental pollution. The method comprises the following steps: coating a hardened layer coating on the surface of a hot-press molding plastic film for in-mold decoration injection molding; simultaneously applying ultraviolet light (UV), Electron Beam (EB) or ultraviolet light plus electron beam (UV + EB) to make the hardened layer paint become a semi-hardened surface hardened layer; the hot-press molding plastic film with the semi-hardening surface hardening layer is applied to an in-mold decoration injection molding process, and the semi-hardening surface hardening layer is completely hardened after deep drawing molding is completed.

Description

Method for producing hardened film applied to in-mold decoration injection molding

technical field

The present invention relates to a kind of in-mold decoration injection molding [In-mold decoration (IMD)] technology, especially a kind of hardened film manufacturing method that is applied to the outer layer surface of the in-mold decoration injection molding (IMD) and has a hardened layer.

Background technique

Traditional plastic processing technology has gradually been unable to meet the requirements of light, thin and short consumer electronics products of modern products, as well as environmental awareness. Due to the advantages of In-mold decoration (IMD) molding, it is suitable for plastic products of 3C, home appliances, LOGO nameplates and auto parts, especially the currently popular mobile phone casings and various instrument panels. Injection molding for in-mold decoration (IMD) can replace many traditional processes, such as thermal transfer, spraying, printing, electroplating and other exterior decoration methods. In particular, multiple color images, backlights, and related products are required. Injection Molding (IMD) is a relatively new automated production process. Compared with other processes, Injection Molding (IMD) can reduce production steps and reduce dismantling of components, so it can save time for rapid production And cost, but also has the advantages of improving quality, increasing image complexity and improving product durability, applied to product appearance, in-mold decoration injection molding (IMD) is the most efficient method, it is on the surface of the film Printing, thermoforming, punching, and finally combined with plastic molding, eliminating the need for secondary operations and man-hours, especially when backlighting, multi-curved surfaces, rib interference, etc. printing and painting processes cannot be handled, it is especially used. Timing of In-Mold Decorative Injection Molding (IMD) process. Take Taiwan Patent No. 00462914 "Injection Molding Method for In-Mold Film Decoration That Can Isolate Electromagnetic Interference" as an example [refer to the patent announcement data on November 11, 2001], the invention includes the following steps: Step 1: Decorative film: Print the desired pattern on one side of a transparent film-like film; Step 2: Coating a masking layer: Coat a metal shielding layer that can isolate electromagnetic interference on the printed and decorated film; Step 3: Film preforming: Put the film coated with the masking layer into the mold, and thermoform it into the desired appearance according to the accessory design; Step 4: Cutting, trimming and positioning in the injection molding mold: cutting and trimming the preformed film to the injection molding mold The size of the cavity, and then put it into and fix it in the injection molding cavity; Step 5: Injection molding: use the injection molding machine to inject the hot-melt resin on the printing side of the formed film, so that the hot-melt resin is cured and combined with the film into one, and finally the finished product is taken out from the injection molding cavity, that is, the steps of the present invention are completed. China Taiwan Announcement No. 00532059 "Case Forming Manufacturing Method with EMI Shielding and Surface Decoration" patent [reference to announcement data on May 11, 2003], which is mainly through A. Forming plastic film steps, B. Forming EMI shielding Layer step, C. Coating step and D. Forming outer layer step and other steps, and the EMI shielding layer can be integrally formed between the plastic film outer layer and the plastic inner layer. Accordingly, an EMI shielding layer can be formed Good results, EMI shielding layer will not wear, weather resistance, chemical resistance, beautiful appearance; moreover, the plastic film can be directly formed with a predetermined decorative surface, and the EMI shielding layer is tied with the plastic film The decorative surface (predetermined pattern or color formed on the plastic film) is formed and combined at one time, so that the cost can be effectively reduced and the manufacturing efficiency can be improved to meet the actual needs of the industry.

As mentioned earlier, on portable electronic products, the outermost layer of the surface must have a hardened layer to prevent the surface from being scratched and destroy the appearance or sense of value of the product. Traditionally, there is a way to do this after the object shape is manufactured. Spraying is used to coat the hardened layer, but this method is cumbersome, has low yield and produces solvent air pollution, which is an environmentally polluting and expensive process.

The use of thermoplastic films in the In-Mold Decorative Injection Molding (IMD) process will replace traditional mold coating, hot stamping and electroplating. This process is more widely used today, including automotive interior and exterior parts and portable electronic products such as mobile phones, Computers, game consoles, etc. The In-Mold Decorative Injection Molding (IMD) process uses thermoplastic films to achieve decorative and colorful effects through printing, coating, and dyeing, and then undergoes mold cutting, thermoforming, trimming, and insertion into the injection cavity Injection molding, the bottom layer is a compatible plastic substrate, the inner surface of the thermoplastic film can be processed into various patterns such as color, metal surface, wood grain, etc., because the pattern color is placed on the inner layer of the thermoplastic film , has the effect of not being destroyed. Another more favorable method is to use a thermoplastic film, first coating a hardened layer on the outer surface of the film, yet this hardened layer must be stretched by thermocompression without cracking, but, in this way The maximum hardness of the hardened layer produced by the method will be limited by the stretch ratio (such as 1.2 or 1.3 times), and currently there is no hardened film with good functions on the market. Autotype International company provides a material for large stretch ratio (deep forming), which is produced by coating and heat drying and can be used in the flat-plate in-mold decoration injection molding (IMD) process (B stage). The coating film can also be deeply formed; after forming, use ultraviolet light (UV) to create a scratch-resistant surface (C stage), but the surface hardness of this material failed to pass the test of pencil hardness F/500g (HB/500g , no scratches through the test), and this technology, in the thermal drying method, the production speed is often limited, and the heat when the coating is drying may also cause damage to the temperature-sensitive substrate film or photoinitiator. . The above is the biggest deficiency of the current technology, and it is actually a problem that the industry needs to overcome.

Contents of the invention

The purpose of the present invention is to provide a hardened film that can avoid cracking when the surface of the hardened film is stretched when it is deeply formed in the In-Mold Decorative Injection Molding (IMD) process, so that the In-Mold Decorative Injection Molding (IMD) process can be adopted by the industry. It is widely used in the world and achieves the effect of improving production yield, efficiency, colorization and reducing environmental pollution. It is a hardened film manufacturing method applied to in-mold decoration injection molding.

A method for manufacturing a hardened film applied to in-mold decoration injection molding, characterized in that the method comprises the following steps: coating a layer of hardened layer paint on the surface of a thermocompressible plastic film for in-mold decoration injection molding; Apply ultraviolet light (UV), electron beam (EB) or ultraviolet light plus electron beam (UV+EB) at the same time to make the hardened layer coating a semi-hardened surface hardened layer; the semi-hardened surface hardened layer can be thermocompressed The plastic film is used in the in-mold decoration injection molding process, and the semi-hardened surface hardening layer is fully hardened after the deep drawing molding is completed.

The beneficial effects of the present invention are: on the surface of the heat-press-formable plastic film used for in-mold decoration injection molding, a surface semi-hardened hardened layer is first produced (such as coating one layer of hardened layer coating, and then irradiated with ultraviolet light or electron beam light) Make the hardened layer coating become a semi-hardened surface hardened layer), when this surface semi-hardened thermoformable plastic film is applied to the in-mold decoration injection molding process, it will not produce a surface hardened layer during deep drawing Cracking phenomenon, after the completion of deep drawing and then use radiation energy (UV/EB/IR) to fully harden the hardened layer, using this method will promote the in-mold decorative injection molding (IMD) process to be adopted by the industry It is widely used to achieve the effects of improving production yield, efficiency, colorization and reducing environmental pollution.

Comparing the In-mold Decoration Injection Molding (IMD) semi-hardening (B stage) forming film used in the present invention through ultraviolet light (UV) or electron beam (EB) or infrared (IR) thermal energy irradiation semi-hardening and thermal drying method semi-hardening advantage:

1. In terms of economic benefits, ultraviolet light (UV) or electron beam (EB) dries faster than heat drying.

2. Ultraviolet light (UV) or electron beam (EB) irradiation will cause less damage to the semi-hardened temperature-sensitive film.

3. Semi-hardening by ultraviolet light (UV) or electron beam (EB) irradiation is more environmentally friendly.

4. Ultraviolet (UV) or electron beam (EB) irradiation semi-hardening has more flexibility in the selection of substrates and photoinitiators.

Detailed ways

The method of the present invention is as follows: it mainly produces a surface semi-hardened hardened layer [such as coating one deck hardened layer paint on the surface of the heat-press-formable plastic film that is used for in-mold decoration injection molding, and then uses ultraviolet light (UV) Or electron beam (EB) makes the hardened layer coating become a semi-hardened (Bstage) surface hardened layer, and the thickness of the hardened layer coating is between 5-15um], so that the surface hardened layer does not cause turtles when used for deep molding. cracked surface hardened film, and then fully harden the semi-hardened surface hardened layer after deep drawing forming [such as to complete deep forming, then use ultraviolet light (UV) or electron beam (EB) or infrared (IR) ) fully irradiated to achieve a fully hardened state, using radiation energy (UV/EB/IR) to fully harden is an existing technology]. In the present invention, ultraviolet light (UV) or electron beam (EB) can be used to irradiate a hardenable coating material, which contains monomers, polymers, diluents, additives, and if necessary, Photoinitiator. This coating can be coated on a film substrate (that is, a plastic film formed by thermocompression), and if necessary, be properly dried; then, the liquid coating will be in a semi-hardened state by irradiating appropriate energy and spectrum of UV or EB light, In later examples we use single or multiple photoinitiators to achieve the proposed hardening effect.

Furthermore, the present invention measures or judges whether the hardened layer paint has entered the semi-hardened (B stage) state that can be used in the In-Mold Decorative Injection Molding (IMD) process, which can be quickly judged by the following methods:

1. Solvent resistance test, drop 1 cc of solvent (for example: ethyl acetate) on the surface of the hardened coating at room temperature at room temperature, wipe it with dry cotton wood after the solvent is completely evaporated, and test the surface of the hardened coating. Whether there is slight corrosion or fogging. Semi-hardened if corrosion or fogging occurs. The fully hardened condition is when there is no corrosion or fogging.

2. Fold the semi-hardened layer upwards and fold the film down 180 degrees by hand, and use a 100-fold microscope to detect the cracked state of the folded line. If there is no crack line at the folded line, it is semi-hardened. If there is a crack line at the position of the broken line, it is a fully hardened state.

3. Use a hard object (such as: nail) to scrape a line on the surface of the semi-hardened layer. If there are grooves and powders are scraped out, it indicates a semi-hardened state. If no grooves appear and no powder is scraped out, it is fully hardened.

Also, after the surface semi-hardened hardened layer film of the present invention is molded under high temperature and high pressure in the In-Mold Decorative Injection Molding (IMD) process, ultraviolet light (UV) or electron beam (EB) or infrared (IR) heat energy ( This is a conventional technique) to irradiate the hardened layer from a semi-hardened (Bstage) state to a fully hardened (C stage) state.

In the following examples we use single or multiple photoinitiators to achieve the proposed hardening effect. Coating acrylic hardening paint with a PC (Polycarbonate film) film with a thickness of 178 μm, and irradiating with an ultraviolet (UV) lamp with an energy of 800mj/cm2, when the coating thickness is 5-15μm and fully hardened, it can reach a standard hardness of 1H/500g. If mercury ultraviolet light (UV) lamp (200mj/cm2) is used for partial hardening (B stage), at room temperature, drop 1cc of solvent (ethyl acetate) on the surface of the hardened layer coating at room temperature, and wait until the solvent is completely Wipe it with dry cotton wood after volatilization, and check whether there is slight corrosion or atomization on the surface of the hardened layer coating. This ensures that the degree of hardening is acceptable for special Injection Molding (IMD) applications. When the semi-hardened (B stage) film is folded, put the semi-hardened layer up and fold the film in half 180 degrees by hand, and use a 100 times microscope to detect the cracking state of the folding line. If there is no cracking line in the folding line, it is semi-hardened state. is acceptable in specific IMD applications. After the semi-hardened (B stage) film is thermoformed by the in-mold injection molding (IMD) process, it is fully irradiated with other mercury-type ultraviolet (UV) lamps, and the hardness can be increased to above F/500g, and the deep forming area No crack lines were generated.

The above is only a preferred feasible embodiment of the present invention, and is not intended to limit the scope of the present invention. For those who are familiar with this art, the alternative manufacturing method done by using the description of the present invention and the scope of the patent application should be Included in the patent scope of the present invention.

Claims (4)

1. A method for producing a hardened film applied to in-mold decoration injection molding, characterized in that: the method comprises the steps of: coating one deck of hardened layer coating on the surface of a thermocompressible plastic film for in-mold decoration injection molding ;Use ultraviolet light, electron beam or ultraviolet light plus electron beam at the same time, so that the hardened layer coating becomes a semi-hardened surface hardened layer; the thermocompressible plastic film with a semi-hardened surface hardened layer is used for in-mold decoration injection In the molding process, the semi-hardened surface hardening layer is fully hardened after the deep drawing molding is completed. 2 . The method for manufacturing a hardened film applied to in-mold decoration injection molding according to claim 1 , wherein the thickness of the hardened layer coating is between 5-15 um. 3. The method for manufacturing a hardened film applied to in-mold decoration injection molding as claimed in claim 1, wherein the incomplete reaction of the semi-hardened surface hardened layer is to use ultraviolet light or electron beams with lower energy than the fully hardened reaction energy to complete. 4. The method of manufacturing a hardened film applied to in-mold decoration injection molding as claimed in claim 1, wherein the incomplete partial reaction of the semi-hardened surface hardened layer uses ultraviolet light or electron beam spectrum different from that of fully hardened irradiated.